Chiral Symmetry Breaking in an External Field

TL;DR

This paper investigates how an external magnetic field influences chiral symmetry breaking in quenched ladder QED, revealing that the field induces symmetry breaking at weak couplings and that phase transitions vary with temperature and chemical potential.

Contribution

It demonstrates that a uniform external magnetic field can induce chiral symmetry breaking at weak couplings in quenched ladder QED, and characterizes the nature of the resulting phase transitions.

Findings

Magnetic field enables spontaneous chiral symmetry breaking at weak couplings.

High temperature restores chiral symmetry via a continuous transition.

High chemical potential restores symmetry via a discontinuous transition.

Abstract

The effects of an external field on the dynamics of chiral symmetry breaking are studied using quenched, ladder QED as our model gauge field theory. It is found that a uniform external magnetic field enables the chiral symmetry to be spontaneously broken at weak gauge couplings, in contrast with the situation when no external field is present. The broken chiral symmetry is restored at high temperatures as well as at high chemical potentials. The nature of the two chiral phase transitions is different: the transition at high temperatures is a continuous one whereas the phase transition at high chemical potentials is discontinuous.